Sept. 5 (Bloomberg) — American employers hired fewer workers than forecast in August and the jobless rate dropped because people left the workforce, bolstering those on the Federal Reserve who want to be more deliberate in removing monetary stimulus.   The 142,000 advance in payrolls was smaller than the lowest estimate in a Bloomberg survey and followed a revised 212,000 gain in July, figures from the Labor Department showed today in Washington. The median estimate was for a 230,000 increase. The unemployment rate fell to 6.1 percent from 6.2 percent in July, reflecting a drop in joblessness among teenagers.   Employers who boosted headcounts in the first half of the year may be more restrained in their hiring as they await even faster economic growth. Fed Chair Janet Yellen and her colleagues will use today's report to help discern the extent of slack in the labor market as they pare back record monetary stimulus, while keeping interest rates low at the same time.   "The shortfall in payrolls is disappointing, but it sure looks like a fluke, not a trend," said Diane Swonk, chief economist at Mesirow Financial Inc. in Chicago. "It gives Yellen a little wiggle room to do what she wants to do, and that is end the tapering and not start raising rates anytime soon."   Stock-index futures pared declines after the report fueled speculation the Fed won't have to raise interest rates soon. The contract on the Standard & Poor's 500 Index expiring this month fell 0.1 percent to 1,995.7 at 9:23 a.m. in New York.

Economists' estimates